This invention involves a method and apparatus for butt-welding two facing and adjoining plastic pipe sections or plastic fittings (hereafter sometimes referred to as "tubular members") which are supported in axially adjustable expansion devices and joined together under axial pressure after heating in the vicinity of the juncture by means of electric heating elements.
There are known methods and apparatus whereby the facing sides of plastic tubular members, which are to be joined, are heated simultaneously by means of a plate-shaped heating element inserted in between. The heating element is swung out after heating, and the headed faces of the plastic tubular members are moved axially and brought together under pressure so that they are joined together. The facing sides, which have been softened, are pushed into each other and deformed, so that a bead is formed at the joint, on both inside and outside. As a result, the inside bead constricts the diameter in the area of the joint, which is often undesirable if not detrimental.